This invention relates to an outboard motor and more particularly to an improvement for cooling the components and particularly the electrical components associated with the engine of an outboard motor.
It is well known that there are a number of substantial design challenges for engineers in connection with outboard motors. Because of the extreme compact nature of an outboard motor, some design problems are presented that are not common in other applications of power plants.
One of the areas where the challenge is the greatest is in the design of the engine and the powerhead. Generally, an outboard motor is comprised of a powerhead and a drive shaft housing lower unit that depends from the powerhead. The powerhead includes a powering internal combustion engine and a surrounding protective cowling. The engine drives a drive shaft which depends into the drive shaft housing and which drives a propulsion device through a transmission in the lower unit for propelling the associated watercraft.
With the tendency to improve performance and reduce weight, the space available for the necessary engine size continues to diminish. This problem is compounded by the fact that an electronic control system is preferably used for controlling portions of the engine operation to improve its efficiency and performance. Many of the components associated with the electrical control system must be cooled in order to operate at their maximum efficiency and to avoid damage.
It has been proposed in connection with outboard motors to mount the electrical components or some of them mounted in proximity to the inlet opening of the protective cowling. Alternatively the components may be mounted on the air silencer or intake device associated with the engine. Examples of these construction can be seen in U.S. Pat. No. 4,632,662 issued Dec. 30, 1986 and entitled "Mounting Structure for an Electronic Parts Unit of an Outboard Engine" and U.S. Pat. No. 5,207,186 issued May 4, 1993 and entitled "Arrangement for Mounting an Electronic Control Unit on an Engine." These devices are effective in ensuring that the electrical components will be well cooled. There are, however, some disadvantages with the structures.
For example, the structure shown in U.S. Pat. No. 4,632,662 mounts the component in proximity to the air inlet of the protective cowling so that the inlet air will flow over the electrical unit for its cooling. However, it is well known that the air that is drawn into the protective cowling through its inlet opening may contain large amounts of water either in vapor or liquid form. Thus, corrosion, shorting, and other problems may result.
U.S. Pat. No. 5,207,186 mounts the control unit on the intake air device of the engine. As such, however, the air flow is relatively minimal and thus this patent uses radiating fins that extend into the air inlet device to assist in cooling. This provides a complicated structure and also may interfere with the efficient airflow to the engine.
It is, therefore, a principal object of this invention to provide an improved component mounting arrangement for an outboard motor.
It is a further object of this invention to provide an improved component mounting arrangement for the electrical components of an outboard motor that will assist in their cooling and ensure against intrusion of high amounts of water vapor on the electronic components.